We have a small bubbling fountain in the garden. It recycles through a pump inside a basin under the water feature. It always looks good at the start of the season after cleaning, but very quickly, within a week or two, it develops sludge and algae. I realise that it must be cleaned out from time to time, but every two weeks seems a little excessive for maintenance. Last year I put some vinegar in the water and that seemed to help. Any suggestions regarding agents that I can put in the water to keep the water clear and discourage cellular growth without harming visiting birds?

What about bleach, or the type of chemicals that they use in hot tubs? I have a very small water feature outside that I don't put bleach in simply because my cats like to drink out of it. Instead, I just flush it out with the hose when I see it getting grimy inside. If you can control it with water plants, that would be the nicest of course, but how effective is that? I would certainly be interested in that option.

U can't leave standing water outside on account of it being used as a breeding space by mosquitoes. So, if u have standing water, u must have goldfish to eat the mosquito larvae. And, if u have fish, u can't use any chemicals.

So a natural pond is the only way to go. No cleaning at all.

Besides, I'm very pleased with the buildup of algae on my fountain. If it didn't occur naturally I would be painting milk or yoghurt on it to encourage algae.

Adopt the pace of nature, her secret is patience......Ralph Waldo Emmerson....

The best thing I have found for cleaning small fountains is Hydrogen Peroxide.Just ad about a half bottle(8 oz) and within 24 hours you will notice a huge difference.It is best used just as the water looks like it's starting to get dirty.

Hydrogen peroxide is basically oxygenated water. It is a powerful oxidizer , but breaks down fairly quickly in open air. A diluted solution of it such as you'd find in adding a half bottle of 3% solution should be safe if pets drink from the fountain. At most, it might fizz in their mouth and make them look elsewhere for a drink. Within a day, most of the peroxide will have broken down and all you would have left is water.

"1. Fish eat algae. I have 10-inch goldfish that started out as tiny 12 cent Wal-Mart fish.2. Plants compete with algae for oxygen and sunlight. Algae hates shade. Algae loses.3. Your pond should be in shade for half the day. Obviously, if it's already built and it's in the sun all day long, you can't help this. Add water plants.4. "Beneficial bacteria". I use Microbe-Lift, available at most pond supply stores. This microscopic bacteria establishes itself in your pond and helps prevent algae bloom.5. Aeration. Waterfall, bubbler, sprayer. Water in motion discourages algae. "

Thanks for all the replies. I have gone with Mollyzone & Dave's suggestion of hydrogen peroxide and put half a bottle in the water just after taking this picture. As you can see it is not suitable for fish or plants (even guppies wouldn't survive, and would end up in the basin underneath.